Github user mhthanh commented on a diff in the pull request:
https://github.com/apache/tajo/pull/156#discussion_r18077565
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+*********************************
+Meta Commands
+*********************************
+
+
+In tsql, anything command that begins with an unquoted backslash ('\') is
a tsql meta-command that is processed by tsql itself.
+
+In the current implementation, there are meta commands as follows: ::
+
+ default> \?
+
+
+ General
+ \copyright show Apache License 2.0
+ \version show Tajo version
+ \? show help
+ \? [COMMAND] show help of a given command
+ \help alias of \?
+ \q quit tsql
+
+
+ Informational
+ \l list databases
+ \c show current database
+ \c [DBNAME] connect to new database
+ \d list tables
+ \d [TBNAME] describe table
+ \df list functions
+ \df NAME describe function
+
+
+ Tool
+ \! execute a linux shell command
+ \dfs execute a dfs command
+ \admin execute tajo admin command
+
+
+ Variables
+ \set [[NAME] [VALUE] set session variable or list session variables
+ \unset NAME unset session variable
+
+
+ Documentations
+ tsql guide http://tajo.apache.org/docs/current/cli.html
+ Query language http://tajo.apache.org/docs/current/sql_language.html
+ Functions http://tajo.apache.org/docs/current/functions.html
+ Backup & restore
http://tajo.apache.org/docs/current/backup_and_restore.html
+ Configuration
http://tajo.apache.org/docs/current/configuration.html
+
+-----------------------------------------------
+Basic usages
+-----------------------------------------------
+
+``\l`` command shows a list of all databases as follows: ::
+
+ default> \l
+ default
+ tpch
+ work1
+ default>
+
+
+
+``\d`` command shows a list of tables in the current database as follows:
::
+
+ default> \d
+ customer
+ lineitem
+ nation
+ orders
+ part
+ partsupp
+ region
+ supplier
+
+
+``\d [table name]`` command also shows a table description as follows: ::
+
+ default> \d orders
+
+ table name: orders
+ table path: hdfs:/xxx/xxx/tpch/orders
+ store type: CSV
+ number of rows: 0
+ volume (bytes): 172.0 MB
+ schema:
+ o_orderkey INT8
+ o_custkey INT8
+ o_orderstatus TEXT
+ o_totalprice FLOAT8
+ o_orderdate TEXT
+ o_orderpriority TEXT
+ o_clerk TEXT
+ o_shippriority INT4
+ o_comment TEXT
+
+
+
+The prompt ``default>`` indicates the current database. Basically, all SQL
statements and meta commands work in the current database. Also, you can change
the current database with ``\c`` command.
+
+.. code-block:: sql
+
+ default> \c work1
+ You are now connected to database "test" as user "hyunsik".
+ work1>
+
+
+``\df`` command shows a list of all buit-in function as follows: ::
+
+ default> \df
+ Name | Result type | Argument types | Description
| Type
+
-----------------+-----------------+-----------------------+-----------------------------------------------+-----------
+ abs | INT4 | INT4 | Absolute
value | GENERAL
+ abs | INT8 | INT8 | Absolute
value | GENERAL
+ abs | FLOAT4 | FLOAT4 | Absolute
value | GENERAL
+ abs | FLOAT8 | FLOAT8 | Absolute
value | GENERAL
+ acos | FLOAT8 | FLOAT4 | Inverse
cosine. | GENERAL
+ acos | FLOAT8 | FLOAT8 | Inverse
cosine. | GENERAL
+ add_days | TIMESTAMP | DATE,INT2 | Return date
value which is added with given pa| GENERAL
+ add_days | TIMESTAMP | DATE,INT4 | Return date
value which is added with given pa| GENERAL
+ add_days | TIMESTAMP | DATE,INT8 | Return date
value which is added with given pa| GENERAL
+ add_days | TIMESTAMP | TIMESTAMP,INT2 | Return date
value which is added with given pa| GENERAL
+ add_days | TIMESTAMP | TIMESTAMP,INT4 | Return date
value which is added with given pa| GENERAL
+ add_days | TIMESTAMP | TIMESTAMP,INT8 | Return date
value which is added with given pa| GENERAL
+ add_months | TIMESTAMP | DATE,INT2 | Return date
value which is added with given pa| GENERAL
+ add_months | TIMESTAMP | DATE,INT4 | Return date
value which is added with given pa| GENERAL
+ add_months | TIMESTAMP | DATE,INT8 | Return date
value which is added with given pa| GENERAL
+ add_months | TIMESTAMP | TIMESTAMP,INT2 | Return date
value which is added with given pa| GENERAL
+ add_months | TIMESTAMP | TIMESTAMP,INT4 | Return date
value which is added with given pa| GENERAL
+ add_months | TIMESTAMP | TIMESTAMP,INT8 | Return date
value which is added with given pa| GENERAL
+ ascii | INT4 | TEXT | ASCII code
of the first character of the argum| GENERAL
+ asin | FLOAT8 | FLOAT4 | Inverse
sine. | GENERAL
+ asin | FLOAT8 | FLOAT8 | Inverse
sine. | GENERAL
+ atan | FLOAT8 | FLOAT4 | Inverse
tangent. | GENERAL
+ atan | FLOAT8 | FLOAT8 | Inverse
tangent. | GENERAL
+ atan2 | FLOAT8 | FLOAT4,FLOAT4 | Inverse
tangent of y/x. | GENERAL
+ atan2 | FLOAT8 | FLOAT8,FLOAT8 | Inverse
tangent of y/x. | GENERAL
+ avg | FLOAT8 | INT8 | the mean of
a set of numbers | AGGREGATIO
+ avg | FLOAT8 | FLOAT4 | The mean of
a set of numbers. | AGGREGATIO
+ avg | FLOAT8 | INT4 | the mean of
a set of numbers. | AGGREGATIO
+ avg | FLOAT8 | FLOAT8 | The mean of
a set of numbers. | AGGREGATIO
+ bit_length | INT4 | TEXT | Number of
bits in string | GENERAL
+ btrim | TEXT | TEXT | Remove the
longest string consisting only of | GENERAL
+ btrim | TEXT | TEXT,TEXT | Remove the
longest string consisting only of | GENERAL
+ cbrt | FLOAT8 | FLOAT4 | Cube root
| GENERAL
+ cbrt | FLOAT8 | FLOAT8 | Cube root
| GENERAL
+ ceil | INT8 | FLOAT4 | Smallest
integer not less than argument. | GENERAL
+ ceil | INT8 | FLOAT8 | Smallest
integer not less than argument. | GENERAL
+ ceiling | INT8 | FLOAT4 | Smallest
integer not less than argument. | GENERAL
+ ceiling | INT8 | FLOAT8 | Smallest
integer not less than argument. | GENERAL
+ char_length | INT4 | TEXT | Number of
characters in string | GENERAL
+ character_length| INT4 | TEXT | Number of
characters in string | GENERAL
+ chr | CHAR | INT4 | Character
with the given code. | GENERAL
+ coalesce | BOOLEAN | BOOLEAN,BOOLEAN_ARRAY | Returns the
first of its arguments that is not| GENERAL
+ coalesce | INT8 | INT8_ARRAY | Returns the
first of its arguments that is not| GENERAL
+ coalesce | FLOAT8 | FLOAT8_ARRAY | Returns the
first of its arguments that is not| GENERAL
+ coalesce | TEXT | TEXT_ARRAY | Returns the
first of its arguments that is not| GENERAL
+ coalesce | DATE | DATE_ARRAY | Returns the
first of its arguments that is not| GENERAL
+ coalesce | TIME | TIME_ARRAY | Returns the
first of its arguments that is not| GENERAL
+ coalesce | TIMESTAMP | TIMESTAMP_ARRAY | Returns the
first of its arguments that is not| GENERAL
+ concat | TEXT | TEXT,TEXT_ARRAY | Concatenate
all arguments. | GENERAL
+ concat_ws | TEXT | TEXT,TEXT,TEXT_ARRAY | Concatenate
all but first arguments with separ| GENERAL
+ cos | FLOAT8 | FLOAT4 | Cosine.
| GENERAL
+ cos | FLOAT8 | FLOAT8 | Cosine.
| GENERAL
+ count | INT8 | ANY | The number
of rows for which the supplied exp| DISTINCT_A
+ count | INT8 | | the total
number of retrieved rows | AGGREGATIO
+ count | INT8 | ANY | The number
of retrieved rows for which the sup| AGGREGATIO
+ current_date | DATE | | Get current
date. Result is DATE type. | GENERAL
+ current_time | TIME | | Get current
time. Result is TIME type. | GENERAL
+ date | INT8 | INT4 | Extracts
the date part of the date or datetime| GENERAL
+ date_part | FLOAT8 | TEXT,TIME | Extract
field from time | GENERAL
+ date_part | FLOAT8 | TEXT,TIMESTAMP | Extract
field from timestamp | GENERAL
+ date_part | FLOAT8 | TEXT,DATE | Extract
field from date | GENERAL
+ decode | TEXT | TEXT,TEXT | Decode
binary data from textual representation| GENERAL
+ degrees | FLOAT8 | FLOAT4 | Radians to
degrees | GENERAL
+ degrees | FLOAT8 | FLOAT8 | Radians to
degrees | GENERAL
+ digest | TEXT | TEXT,TEXT | Calculates
the Digest hash of string | GENERAL
+ div | INT8 | INT8,INT8 |
Division(integer division truncates results) | GENERAL
+ div | INT8 | INT8,INT4 |
Division(integer division truncates results) | GENERAL
+ div | INT8 | INT4,INT8 |
Division(integer division truncates results) | GENERAL
+ div | INT8 | INT4,INT4 |
Division(integer division truncates results) | GENERAL
+ encode | TEXT | TEXT,TEXT | Encode
binary data into a textual representati| GENERAL
+ exp | FLOAT8 | FLOAT4 | Exponential
| GENERAL
+ exp | FLOAT8 | FLOAT8 | Exponential
| GENERAL
+ find_in_set | INT4 | TEXT,TEXT | Returns the
first occurrence of str in str_arr| GENERAL
+ floor | INT8 | FLOAT4 | Largest
integer not greater than argument. | GENERAL
+ floor | INT8 | FLOAT8 | Largest
integer not greater than argument. | GENERAL
+ geoip_country_co| TEXT | TEXT | Convert an
ipv4 address string to a geoip coun| GENERAL
+ geoip_country_co| TEXT | INET4 | Convert an
ipv4 address to a geoip country cod| GENERAL
+ geoip_in_country| BOOLEAN | TEXT,TEXT | If the
given country code is same with the cou| GENERAL
+ geoip_in_country| BOOLEAN | INET4,TEXT | If the
given country code is same with the cou| GENERAL
+ initcap | TEXT | TEXT | Convert the
first letter of each word to upper| GENERAL
+ left | TEXT | TEXT,INT4 | First n
characters in the string. | GENERAL
+ length | INT4 | TEXT | Number of
characters in string. | GENERAL
+ locate | INT4 | TEXT,TEXT | Location of
specified substring | GENERAL
+ locate | INT4 | TEXT,TEXT,INT4 | Location of
specified substring | GENERAL
+ lower | TEXT | TEXT | Convert
string to lower case | GENERAL
+ lpad | TEXT | TEXT,INT4 | Fill up the
string to length length by prepend| GENERAL
+ lpad | TEXT | TEXT,INT4,TEXT | Fill up the
string to length length by prepend| GENERAL
+ ltrim | TEXT | TEXT | Remove the
longest string containing only char| GENERAL
+ ltrim | TEXT | TEXT,TEXT | Remove the
longest string containing only char| GENERAL
+ max | INT4 | INT4 | the maximum
value of expr | AGGREGATIO
+ max | INT8 | INT8 | the maximum
value of expr | AGGREGATIO
+ max | FLOAT4 | FLOAT4 | the maximum
value of expr | AGGREGATIO
+ max | FLOAT8 | FLOAT8 | the maximum
value of expr | AGGREGATIO
+ max | TEXT | TEXT | the maximum
value of expr | AGGREGATIO
+ md5 | TEXT | TEXT | Calculates
the MD5 hash of string | GENERAL
+ min | INT4 | INT4 | the minimum
value of expr | AGGREGATIO
+ min | INT8 | INT8 | the minimum
value of expr | AGGREGATIO
+ min | FLOAT4 | FLOAT4 | the minimum
value of expr | AGGREGATIO
+ min | FLOAT8 | FLOAT8 | the minimum
value of expr | AGGREGATIO
+ min | TEXT | TEXT | the minimum
value of expr | AGGREGATIO
+ mod | INT8 | INT8,INT8 | Remainder
of y/x | GENERAL
+ mod | INT8 | INT8,INT4 | Remainder
of y/x | GENERAL
+ mod | INT8 | INT4,INT8 | Remainder
of y/x | GENERAL
+ mod | INT8 | INT4,INT4 | Remainder
of y/x | GENERAL
+ now | TIMESTAMP | | Get current
time. Result is TIMESTAMP type. | GENERAL
+ octet_length | INT4 | TEXT | Number of
bytes in string. | GENERAL
+ pi | FLOAT8 | | "??"
constant | GENERAL
+ pow | FLOAT8 | FLOAT4,FLOAT4 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | FLOAT4,FLOAT8 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | FLOAT8,FLOAT4 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | FLOAT8,FLOAT8 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | INT4,INT4 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | INT4,INT8 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | INT8,INT4 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | INT8,INT8 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | INT4,FLOAT4 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | INT4,FLOAT8 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | INT8,FLOAT4 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | INT8,FLOAT8 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | FLOAT4,INT4 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | FLOAT4,INT8 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | FLOAT8,INT4 | x raised to
the power of y | GENERAL
+ pow | FLOAT8 | FLOAT8,INT8 | x raised to
the power of y | GENERAL
+ quote_ident | TEXT | TEXT | Return the
given string suitably quoted to be | GENERAL
+ radians | FLOAT8 | FLOAT8 | Degrees to
radians | GENERAL
+ radians | FLOAT8 | FLOAT4 | Degrees to
radians | GENERAL
+ random | INT4 | INT4 | A
pseudorandom number | GENERAL
+ rank | INT8 | | The number
of rows for which the supplied exp| WINDOW
+ regexp_replace | TEXT | TEXT,TEXT,TEXT | Replace
substring(s) matching a POSIX regular| GENERAL
+ repeat | TEXT | TEXT,INT4 | Repeat
string the specified number of times. | GENERAL
+ reverse | TEXT | TEXT | Reverse str
| GENERAL
+ right | TEXT | TEXT,INT4 | Last n
characters in the string | GENERAL
+ round | INT8 | FLOAT4 | Round to
nearest integer. | GENERAL
+ round | INT8 | FLOAT8 | Round to
nearest integer. | GENERAL
+ round | INT8 | INT4 | Round to
nearest integer. | GENERAL
+ round | INT8 | INT8 | Round to
nearest integer. | GENERAL
+ round | FLOAT8 | FLOAT8,INT4 | Round to s
decimalN places. | GENERAL
+ round | FLOAT8 | INT8,INT4 | Round to s
decimalN places. | GENERAL
+ row_number | INT8 | | the total
number of retrieved rows | WINDOW
+ rpad | TEXT | TEXT,INT4 | Fill up the
string to length length by appendi| GENERAL
+ rpad | TEXT | TEXT,INT4,TEXT | Fill up the
string to length length by appendi| GENERAL
+ rtrim | TEXT | TEXT | Remove the
longest string containing only cha| GENERAL
+ rtrim | TEXT | TEXT,TEXT | Remove the
longest string containing only cha| GENERAL
+ sign | FLOAT8 | FLOAT8 | sign of the
argument (-1, 0, +1) | GENERAL
+ sign | FLOAT8 | FLOAT4 | sign of the
argument (-1, 0, +1) | GENERAL
+ sign | FLOAT8 | INT8 | sign of the
argument (-1, 0, +1) | GENERAL
+ sign | FLOAT8 | INT4 | sign of the
argument (-1, 0, +1) | GENERAL
+ sin | FLOAT8 | FLOAT4 | Sine.
| GENERAL
+ sin | FLOAT8 | FLOAT8 | Sine.
| GENERAL
+ sleep | INT4 | INT4 | sleep for
seconds | GENERAL
+ split_part | TEXT | TEXT,TEXT,INT4 | Split
string on delimiter and return the given| GENERAL
+ sqrt | FLOAT8 | FLOAT8 | Square root
| GENERAL
+ sqrt | FLOAT8 | FLOAT4 | Square root
| GENERAL
+ strpos | INT4 | TEXT,TEXT | Location of
specified substring. | GENERAL
+ strposb | INT4 | TEXT,TEXT | Binary
location of specified substring. | GENERAL
+ substr | TEXT | TEXT,INT4 | Extract
substring. | GENERAL
+ substr | TEXT | TEXT,INT4,INT4 | Extract
substring. | GENERAL
+ sum | INT8 | INT8 | the sum of
a distinct and non-null values | DISTINCT_A
+ sum | INT8 | INT8 | the sum of
a set of numbers | AGGREGATIO
+ sum | INT8 | INT4 | the sum of
a set of numbers | AGGREGATIO
+ sum | INT8 | INT4 | the sum of
a distinct and non-null values | DISTINCT_A
+ sum | FLOAT8 | FLOAT8 | the sum of
a set of numbers | AGGREGATIO
+ sum | FLOAT8 | FLOAT4 | the sum of
a set of numbers | AGGREGATIO
+ sum | FLOAT8 | FLOAT4 | the sum of
a distinct and non-null values | DISTINCT_A
+ sum | FLOAT8 | FLOAT8 | the sum of
a distinct and non-null values | DISTINCT_A
+ tan | FLOAT8 | FLOAT4 | Tangent.
| GENERAL
+ tan | FLOAT8 | FLOAT8 | Tangent.
| GENERAL
+ to_bin | TEXT | INT8 | Returns n
in binary. | GENERAL
+ to_bin | TEXT | INT4 | Returns n
in binary. | GENERAL
+ to_char | TEXT | TIMESTAMP,TEXT | Convert
time stamp to string. Format should be| GENERAL
+ to_date | DATE | TEXT,TEXT | Convert
string to date. Format should be a SQL| GENERAL
+ to_hex | TEXT | INT4 | Convert the
argument to hexadecimal | GENERAL
+ to_hex | TEXT | INT8 | Convert the
argument to hexadecimal | GENERAL
+ to_timestamp | TIMESTAMP | TEXT,TEXT | Convert
string to time stamp | GENERAL
+ to_timestamp | TIMESTAMP | INT4 | Convert
UNIX epoch to time stamp | GENERAL
+ to_timestamp | TIMESTAMP | INT8 | Convert
UNIX epoch to time stamp | GENERAL
+ trim | TEXT | TEXT | Remove the
longest string consisting only of | GENERAL
+ trim | TEXT | TEXT,TEXT | Remove the
longest string consisting only of | GENERAL
+ upper | TEXT | TEXT | Convert
string to upper case. | GENERAL
+ utc_usec_to | INT8 | TEXT,INT8 | Extract
field from time | GENERAL
+ utc_usec_to | INT8 | TEXT,INT8,INT4 | Extract
field from time | GENERAL
+
+ (181) rows
+
+
+``\df [function name]`` command also shows a function description as
follows: ::
+
+ default> \df trim
+ Name | Result type | Argument types | Description
| Type
+
-----------------+-----------------+-----------------------+-----------------------------------------------+-----------
+ trim | TEXT | TEXT | Remove the
longest string consisting only of | GENERAL
+ trim | TEXT | TEXT,TEXT | Remove the
longest string consisting only of | GENERAL
+
+ (2) rows
+
+ Function: TEXT trim(text)
+ Description: Remove the longest string consisting only of characters
in characters (a space by default) from the start and end of string.
--- End diff --
"only of characters in characters" -> this makes me confused :-)
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